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Antibiotic of Last Resort Faces New Superbug Threat

A resistant bacterial strain has emerged in Chinese livestock and is spreading quickly.

Could this be the beginning of the end of the antibiotic era?

Widespread use of antibiotics in industrial agriculture to promote the growth of livestock and prevent disease in overcrowded factory farms has been fingered as the key culprit in the rise of antibiotic-resistant bacteria known as superbugs. Now, a heavy-hitting antibiotic that doctors have relied on as a last-ditch treatment for some of the worst superbugs appears in danger of losing its effectiveness as well—and it is losing it quickly.

The drug is colistin, and it dates to the 1950s. Yes, it was great at killing disease-causing bacteria—but it also could wreak havoc on a person’s kidneys. So the medical community largely abandoned colistin for newer, safer antibiotics in the 1970s. But farmers didn’t. Not only did they continue using colistin, but they snatched up all sorts of medically important antibiotics as well, often mixing the drugs at low levels into animal feed on a daily basis.

Fast-forward to today (not a huge chronological leap, when you think about it), and we’re watching antibiotics that were once hailed as miracle drugs increasingly lose their ability to fight disease. With fewer effective antibiotics left in their arsenal to prescribe for the worst antibiotic-resistant infections, doctors have had to turn again to colistin, even though they had deemed the drug too dangerous to prescribe not so long ago.

But even colistin’s days as a disease fighter may be numbered. In November, Chinese researchers announced they had discovered a gene that conferred resistance to colistin and was capable of being transmitted among bacteria. Where had they found bacteria with this gene? In pigs—in pork—and in bacterial samples from hospital patients. It should come as no surprise that Chinese agriculture is one of the world’s largest users of colistin. In quick succession, researchers in at least 10 countries in Southeast Asia, Africa, and Europe announced they had found the gene within their borders.

This week, EU drug regulators said they would undertake an immediate review of colistin’s use in agriculture. “Because of [colistin’s] important role as a last defense against antimicrobial-resistant bacteria, the agency will consider if its 2013 advice on the responsible use of colistin in animals, particularly pigs, needs to be updated in light of the recent discovery,” the European Medicines Agency said in a statement, noting that it expects to finalize its update over the next six months.

But in the face of an ever more alarming crisis posed by antibiotic resistance, that six months can feel like more bureaucratic foot dragging—the kind of delay that those familiar with the Food and Drug Administration in the U.S., which has been shockingly lax in addressing the issue, will find familiar. After all, as the BBC reported last December, experts in the U.K. “thought they had three years before colistin-resistance would spread from China to the UK.” Instead, it’s on their doorstep today.